The present invention relates to an article storage system for handling containers as articles, which may contain semiconductors (wafers).
A conventionally known article storage system of this type includes a rack for storing articles in it and a loader/unloader for loading and unloading the rack.
Japanese patent laid-open publication No. 5-294410 discloses a loader/unloader including a carriage that can run along the front of a shelf, a post standing on the carriage, a lift supported and guided by the post, and a protruder/retractor carried by the lift. The lift includes a rotary table.
The protruder/retractor includes a folding arm mounted on the rotary table of the lift and an article support (fork) connected to the free end of the arm. The rotation of the rotary table causes the folding arm to protrude and retract the article support relative to the shelf.
FIGS. 11a and 11b show a container 101 containing semiconductors (wafers) as articles handled by the known storage system. The container 101 consists of a body 102 including a storage section, where the semiconductors are stored, a neck 103 and a head 104. The neck 103 connects the head 104 and body 102 together and is narrower than them. The head 104 and body 102 define an engaging space 105 between them around the neck 103. The engaging space 105 may generally be used for a robot or another transferrer to catch or hold the container 101 while the container is carried.
FIGS. 11-13 show a rack consisting of vertically spaced horizontal rows of shelves 107. Each shelf 107 includes a deck 108 formed on its top side, where a container 101 can be placed and supported. Each shelf 107 has a space 110 formed through it, through which the article support (fork) 109 of the protruder/retractor can move relatively up and down.
The loader/unloader can load containers 101 on and unload containers 101 from the rack 111. As shown in FIG. 11a, the process for loading a container 101 on each shelf 107 includes protruding the article support 109 of the protruder/retractor from its retracted position over the rotary table 112 of the lift to a position (shown with two-dot chain lines in FIG. 13) over the shelf 107, with the container 101 supported on the support 109. Subsequently, the lift of the loader/unloader is moved downward so that, as shown in FIG. 11b, the article support 109 can move downward through the space 110 of the shelf 107. This transfers the container 101 from the article support 109 onto the deck 108 of the shelf 107, where the container 101 can be stored. Thereafter, as shown with solid lines in FIG. 13, the empty support 109 positioned under the shelf 107 is retracted to its retracted position over the rotary table 112 of the lift.
It is possible to unload a container 101 from each shelf 107 by operating the article support 109 with the process reverse to the loading process.
As shown in FIG. 12, one container 101 can be placed on each shelf 107. Therefore, the storage of a number of containers 101 in the rack 111 needs the same number of shelves 107, and the storage of a large number of containers 101 in the rack 111 needs the large number of shelves 107, raising the cost.
For storage of containers 101 in three vertically spaced horizontal rows a, b and c in the rack 111, it is necessary to provide shelves 107 for the middle row c between the top row a and bottom row b. This increases the vertical distance d between the shelves 107 for the top row a and bottom row b, increasing the height of the rack 111.
As shown in FIG. 13, the width W1 of the article support 109 of the loader/unloader is narrower than the width W2 of each shelf 107. Consequently, when the lift of the loader/unloader moves up and down with a container 101 supported on the article support 109, and when the carriage runs with a container 101 so supported, the container (article) 101 on the article support (fork) 109 may be unstable.
The object of the present invention is to provide an article storage system including a rack lower in height that consists of a smaller number of shelves and a fork that can more stably support an article.
An article storage system according to the present invention is an article storage system for storing therein an article having engaging means. The storage system includes a shelf for supporting the article and a loader/unloader for loading and unloading the shelf. The shelf includes a deck formed on the upper side thereof, on which the article can be placed. The shelf also includes an engaging part formed on the lower side thereof for engaging with the engaging means of the article to hold the article under the shelf. The engaging means and the engaging part can engage with and disengage from each other in the directions in which the article can be loaded and unloaded.
It is possible to store the article in the storage system by either placing the article on the shelf or holding the article hanging from the shelf. Specifically, the article supported by the loader/unloader can be placed on the deck on the upper side of the shelf, or the engaging means of the article supported by the loader/unloader can be engaged with the engaging part on the lower side of the shelf. This makes it possible to support two articles on the upper and lower sides of one shelf. It is consequently possible to greatly reduce the number of shelves to lower the cost in comparison with the conventional system.
The article may have a positioning hole formed in the bottom thereof. The loader/unloader and the shelf deck may each include a positioning protrusion that can engage with and disengage from the positioning hole.
In this case, it is possible to place the article on the shelf deck, with the positioning protrusion of the deck inserted into the positioning hole of the article so that the article can be positioned reliably on the deck. This prevents the article from shifting on and falling from the deck due to an earthquake or another vibration. The loader/unloader can load and unload the article, with the positioning protrusion of the loader/unloader inserted into the positioning hole of the article so that the article can be positioned reliably relative to the loader/unloader as well. Therefore, the article can be put into storage and taken out of storage without shifting so greatly due to vibration of the operating loader/unloader that the article cannot be transferred normally to the shelf, or without falling from the loader/unloader.
The shelf may consist of vertically spaced horizontal rows of shelves. The loader/unloader may consist of a movable unit that can move vertically and horizontally and a fork carried by the movable unit for moving toward and away from the shelf to scoop the article. The positioning protrusion may be formed on the fork.
In this case, it is possible to load an article on each shelf and unload the article from the shelf by moving the movable unit of the loader/unloader vertically and horizontally to position the fork in front of the shelf. By making the positioned fork carry out a series of article transferring operations, it is possible to load the article on and unload the article from either the upper side or the lower side of the shelf. The transferring operations include protruding the fork toward the shelf, moving the fork vertically and retracting the fork toward the movable unit. When the article supported by the fork is put into storage and taken out of storage in this way, the positioning protrusion of the fork is inserted into the positioning hole of the article. This positions the article relative to the fork, preventing the article from shifting so greatly on the fork due to vibration of the moving fork that the article cannot be transferred normally to the shelf, or from falling off the fork.
For storage of three vertically spaced horizontal rows of articles, there is no need for middle shelves between the top and bottom shelves as is necessary for the conventional storage system. The omission of the middle shelves reduces the space between the top and bottom shelves, lowering the height of the rack consisting of vertically spaced horizontal rows of shelves.
The fork may be wider than the shelf and formed with a space through which the shelf can move vertically relative to the fork.
In this case, when the shelf is loaded and unloaded by means of the fork of the loader/unloader, the shelf moves up and down relatively through the space of the fork. Therefore, while the fork is operating, it does not interfere with the shelf. Because the fork is wider than the shelf, however, the fork can stably support an article.
The specific structure and operation of the present invention should be understood more easily from the following description of a preferred embodiment of the invention with reference to the accompanying drawings.